<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
        <style>
            .pink {
                background-color: pink;
            }
        </style>
    </head>
    <body>
        <button class="pink">按钮1</button>
        <button>按钮2</button>
        <button>按钮3</button>
        <button>按钮4</button>
        <script>
            let bts = document.querySelectorAll('button')
            for (let i = 0; i < bts.length; i++) {
                bts[i].addEventListener('click', function () {
                    document.querySelector('.pink').className = ''
                    this.className = 'pink'
                })
            }
        </script>
    </body>
</html>